


A Single Smirk

by LetsTussleBoiz



Series: The Emotions of a Mercenary [1]
Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: F!Byleth is really hot and it's driving Edelgard crazy, F/F, Maybe a little Tsundere, Pre-Relationship, Pre-Time Skip, Slow Burn
Language: English
Status: Completed
Published: 2019-09-14
Updated: 2019-09-14
Packaged: 2020-11-02 05:47:33
Rating: Teen And Up Audiences
Warnings: Major Character Death
Chapters: 1
Words: 2,327
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20641820
Author URL: https://archiveofourown.org/users/LetsTussleBoiz/pseuds/LetsTussleBoiz
Summary: Edelgard was incredibly pleased when the blue-haired mercenary decided to instruct her class. However, as the days go by she is increasingly worried that she has made a mistake. The Professor is impossible to read, and something about her makes Edelgard's heart lurch.





	A Single Smirk

**Author's Note:**

> Hi, y'all! I'm so happy you found my little fanfic. I've read about every Edeleth fanfic I can get my hands on, and at a certain point I just decided to write one myself or I'd go crazy. They're so cute!!! I JUST!!! LET THEM BE HAPPY OKAY!!!
> 
> I say that, but I have plans. Sinister ones. Muhahahaha?
> 
> Anyways, I hope you enjoy the first part! There are roughly... 19 Works planned? They all follow the canon timeline, so the 19th would end with the finale of Crimson Flowers. As soon as we get to the point of spoilers I'll start tagging it as such. 
> 
> This fiction will be fluff for the most part. I might make an offshoot NSFW version at a point where I cut to black in the future if there's enough desire for it. For now, enjoy some cute fluff and Dorothea being smug. (She has the right! Dorothea is like the ONLY ONE in the Black Eagle house to understand romance in any capacity.)

##  Chapter 1

Edelgard narrowed her eyes, lilac irises dilating slightly as she desperately searched for even the slightest tell in her new professor’s face.

Initially, Edelgard had been taken by the tremendous talent of the blue-haired mercenary. After Byleth had saved her life while simultaneously dispatching the bandits with ease, Edelgard had moved quickly. She was determined to sway the woman to join her house. Now, a part of her wondered if that was a mistake. Inviting someone who was simultaneously impossible to read and incredibly observant felt dangerous. 

In the short time since Byleth had taken on the role of teacher for the Black Eagle house, she had accomplished much. She prevented Bernadetta from returning to her room out of fear without making the girl die of fright, convinced Linhardt to stay awake during lectures, and even quieted the clamorous young Caspar.

Byleth set down her chalk, taking a few steps to the side to allow the class to observe her diagram. Edelgard blinked rapidly, taking in the unorthodox formation the professor had drawn. Byleth turned away from the board, her serene gaze settling on Dorothea. “Miss Arnault, would you care to take a guess as to why I have positioned the cavalry here?”

_ Goodness, even her voice is impossible to read, _Edelgard thought glumly. For someone who prided themselves on being able to read others, she was doing a poor job of it here. 

Dorothea smiled, pushing her chair back and approaching the board. She gave the professor a wink as she walked past. “Just Dorothea is fine, Professor.”

Edelgard did her best not to roll her eyes. She considered Dorothea a good friend, but the girl’s tendency to flirt with anyone and everyone was a bit silly. Granted, this was the first time she’d seen her try to come on to a woman, but Edelgard wouldn’t put it past Dorothea to have an eye for both sides of the court.

She watched with interest as the two chatted at the board, Dorothea doing her best to follow the complex drawing. It was far more advanced than the tactics the professor had previously been teaching. Unsurprisingly, Dorothea missed a few important details.

“While your guess was close Dorothea,” Byleth said smoothly in response, “you ignored a crucial part of the situation. If I had followed through with your plan, the cavalry would have fallen prey to the archers positioned on the hilltop.”

Gesturing for Dorothea to return to her seat, Byleth’s gaze settled on Edelgard. The Heiress did her best not to squirm under the scrutinizing stare of her teacher, but it was far from easy. Her eyes felt as if they tore down even the thickest of her walls.

“Edelgard,” Byleth gestured to the board behind her, “would you care to discern what Dorothea was missing in her explanation?”

“Certainly, Professor.” Edelgard strode to the board, hoping her posture displayed confidence to the other students. “While Dorothea is correct that the cavalry are well positioned for a shock tactic, you aptly pointed out the threat of the archers. A better approach would be to utilize our own archers, softening the right flank of the enemy before slamming the cavalry into the weakened line.”

Smiling, Edelgard turned for acknowledgement. Byleth was mere inches from her face, inspecting her closely. Feeling her jaw tighten, Edelgard tried her best to remain firm. 

“And what of the enemy cavalry?” Byleth questioned.

Edelgard frowned. “They’re positioned too far away from the right flank to fill the gap in time, and are in a poor position to retaliate against our own charge due to the high cliffs.”

Nodding, Byleth gestured to another piece of the board. “And the magic casters?”

Despite her position as heiress to the Adrestian Empire, Edelgard found herself sweating under the continued questioning and intense gaze of her teacher. The absence of her usual steadiness caused her next words to stutter. “T-the cavalry could have a caster riding with them, ready to protect against offensive magic while simultaneously bolstering the strength of the charge.”

Byleth’s deep blue eyes fixed on her for a few more seconds. Edelgard wondered if she had ever seen something as blue in all of her travels. When Byleth eventually nodded, Edelgard felt her entire body relax. “Well observed, Edelgard.” She said, tapping her hip with a piece of chalk as she turned to continue with her example.

Bowing to the professor, she returned to her seat. Edelgard hoped the internal panic she felt did not show on her face. As she pulled back her chair, a sultry giggle caught her attention. Edelgard did not enjoy the grin Dorothea was giving her. “And what is so funny, Dorothea?”

“Oh, nothing.”

Her attitude had diverged from annoying and was plummeting towards insufferable.

“Spit it out already.” Edelgard hissed through her teeth, eyes darting between the songstress and her teacher.

“You’re no fun, Edie.” Dorothea complained, pursing her lips. “I was simply enjoying the show you and our dear professor put on.”

“Show?”

“Of course! Don’t tell me you haven’t noticed that she grills you harder than the others? Outside of lectures, our professor speaks more to you than she does to everyone else combined.” Dorothea gave her a smirk, a spark in her eyes that Edelgard didn’t quite recognize.

“Exaggeration is the first step towards dishonesty, Dorothea.” Edelgard chided, turning her head pointedly to focus on the lecture. Thankfully, Dorothea said nothing more on the subject, content with a chuckle.

Edelgard frowned. She had noticed that her teacher seemed to focus on her during classes. If it were anyone else, Edelgard would assume they were trying to butter her up due to her status as the future emperor. However, something told her that Byleth wasn’t like that.

_ So why does she push me so hard? _

Sighing, she did her best to push that line of thinking out of her head. _ I’m sure the professor has her reasons, _ Edelgard thought, _ and I have more important things to worry about.  
_

* * *

  
Ferdinand grunted, falling hard on his backside. He struggled to get back on his feet, but was halted by a wooden blade resting against his neck.

“A true noble knows when to admit defeat. You have bested me, professor.” Ferdinand relented. Byleth nodded, offering him her right hand in place of the sword. Edelgard blinked. 

_ When did she sheath her sword? _She thought, brow furrowing slightly.

Even after witnessing her professor in battle on the night they had met, she was still taken aback by the deadliness in each of her strikes.

“A shame she did not use a real sword,” Someone grumbled behind her, “or we would have one less pest to deal with.”

Edelgard turned, smiling at her faithful attendant. His appearance was well-kempt like usual, oily black hair slicked behind his head. A large bang covered the right side of his face, giving him a sinister vibe. Edelgard was quite certain he styled his own hair for that very reason.

“I keep asking you to teach me how you can read my thoughts so well, Hubert.” She remarked. “And you should not be so harsh on Ferdinand. True, he is an annoying pest at times with his constant clamouring of superiority. But his straightforwardness makes him easy to read. Allies like that are rare.”

She turned back to the training grounds, watching with interest as Byleth danced around the rapid strikes of Caspar’s fists. The professor had a lithe form, her toned muscles flowing like water as she ducked under an aggressive strike from the young knight. Using the momentum, Byleth slid underneath his arm, coming to a stop behind him. She rested her sword against Caspar’s shoulder, eliciting a groan from her opponent. 

Byleth relaxed her form, scanning her row of students in search of her next sparring partner. Her eyes locked with Edelgard’s, and she cocked an eyebrow slightly. Edelgard blushed, averting her gaze as she realized she had been staring.

Hubert narrowed his eyes. “While your words hold truth, your Majesty, I feel that it would be simple to find a more suitable replacement. In addition, I would ensure his death is a painless one.”

She chuckled, giving him a sidelong glance. “Would you really, Hubert? That would be quite generous by your standards.”

Her attendant gave one of his patented sinister smiles. “Well, maybe a little bit of suffering.”

Byleth cleared her throat, causing Edelgard to jump slightly. Barely repressing a shriek not befitting of royalty, she turned. Byleth was standing just behind them, tapping her wooden practice blade against her hip. “Edelgard, would you care to spar?”

“Y-yes, of course, Professor.” Edelgard did her best to ignore her rapid heartbeat as she strode over and plucked a wooden axe from the weapon rack, turning to face the ex-mercenary. The woman was eyeing her critically, taking a few practice swings of her sword as she waited.

Exhaling deeply, Edelgard raised her axe as she took her stance. “Ready, Professor.”

For a moment, the whole arena was still. Edelgard was faintly aware of the interest her fellow classmates had on this bout in particular. She was the best close quarters fighter of the entire class, having bested even a few professors in the past few years. Her grip tightened on the axe handle as she stared at Byleth, and she wondered if she was supposed to make the first move.

Byleth answered her question with a terrifyingly quick dash. Edelgard barely managed to raise her axe handle in time to block the blow that would have taken her at the neck. She felt her teeth chatter as the strike sent vibrations up her arms.

_ That strike could have seriously injured me if I had not managed to block. _ Edelgard thought, backstepping to gain some distance for her swing. _ She’s serious! _

Byleth stayed with her, stepping in time to bring her sword up towards Edelgard’s chest. She rolled to the right, rising with a swing of the hatchet. The professor deftly avoided the strike, seeming to glide along the patterns in the air Edelgard was making with each attack. Edelgard let out a small “Eep!” as Byleth stepped inside her guard, mere inches from her face.

Edelgard tried to maintain a neutral expression as she felt Byleth’s sword resting against her side. “My loss, Professor.”

She brushed a strand of white hair out of her face, trying her best not to feel disappointed. Edelgard had not managed to last more than a minute against her professor. She was not a prideful woman, but it frustrated her nonetheless.

Byleth’s eyes narrowed. “Again.”

Blinking, Edelgard took a step back. “What?”

The professor’s next strike nearly took her head off. Edelgard barely ducked out of the way, stepping back to gain some distance. Byleth was on her once again, each swing of her blade a flash. Continuing to be pushed back, Edelgard was getting frustrated. She took a deep breath to focus herself. As Byleth’s next strike moved to take her at the stomach, she stepped into the attack.

For the first time since the duel started, she caught her professor by surprise. Edelgard’s axe hilt took the sword at the base, softening the blow. Planting her foot firmly, Edelgard let go of her two handed axe grip. She slammed her fist into the leather plating of Byleth’s shoulder, staggering her. Eyes alight, Edelgard brought her left arm up, axe in hand. _ I can do this. _She thought, ignoring the pain in her hand as she brought the heft of her axe down on Byleth.

In an instant, Edelgard was on the ground.

Her head spun slightly at the sudden change in perspective. She groaned, rising to a sitting position. Byleth was standing over her, sweat dripping from her brow. Her breath was visible in the cold morning air, the only sign that Byleth had exerted any effort at all.

“Well done, Edelgard.” Byleth deadpanned, offering her a hand. “That attack was unorthodox and left you open to counter attack, but with more practice it could make for a deadly surprise strike.”

Her face burning slightly, Edelgard took her hand. “Thank you, Professor.”

The moment was interrupted as her class erupted into cheering. Edelgard was startled by the sudden uproar, realizing that she had tuned everything out in order to survive Byleth’s onslaught.

Dorothea trotted up, holding a white towel with a floral trim. She offered it to Edelgard, grinning. “See what I mean, Edie?”

Edelgard didn’t respond, instead opting to snatch the towel from her grasp to cover her face. It wouldn’t do well for her classmates to see their future emperor blushing like a maiden.

Byleth clapped her hands, drawing the attention of her class. “All right, everyone. That does it for today. Tomorrow will be a follow up on today’s sparring.”

“Are you sure you’re not calling it a day because Edelgard tired you out, Teach?” Caspar hollered, grinning.

Rather than responding, Byleth simply stared at him. Edelgard watched with amusement as the laughter died in the young boy’s throat.

_ Wait… _ Edelgard thought, doing a double take. _ Is the Professor… smirking? _

Sure enough, the Professor was smirking at Caspar, a single eyebrow raised. It was subtle, difficult to notice if you weren’t already looking. _ But you’re always looking at the professor nowadays, aren’t you? _Her mind supplied, much to her distaste.

“You’re a bit red in the face, Edie. Are you all right?” Dorothea asked.

“I’m fine, Dorothea.” Edelgard snapped back. “An Emperor does not get ill.”

She watched as Byleth returned her sword to the rack, trying her best to ignore the way her stomach lurched as Byleth bent over to snatch a towel from the pile.

Dorothea followed her gaze, smiling. “It really is a splendid sight, isn’t it?”

Edelgard pushed past her, trying to ignore how hot her face felt. “I have no idea what you’re talking about.”

“Right.” Dorothea said, smirking. “Of course you don’t, Edie.”


End file.
